Feature: Added support for displaying total duration when selecting multiple video files (#15476)

Author: hishitetsu

src/Files.App/ViewModels/Properties/Items/CombinedFileProperties.cs

@@ -51,7 +51,13 @@ await LocationHelpers.GetAddressFromCoordinatesAsync((double?)list.Find(
 				var props = queries.SelectMany(query => query!.First(section => section.Key == group.Key));
 				foreach (FileProperty prop in group)
 				{
-					if (props.Where(x => x.Property == prop.Property).Any(x => !Equals(x.Value, prop.Value)))
+					if (prop.Property == "System.Media.Duration")
+					{
+						ulong totalDuration = 0;
+						props.Where(x => x.Property == prop.Property).ForEach(x => totalDuration += (ulong)x.Value);
+						prop.Value = totalDuration;
+					}
+					else if (props.Where(x => x.Property == prop.Property).Any(x => !Equals(x.Value, prop.Value)))
 					{
 						// Has multiple values
 						prop.Value = prop.IsReadOnly ? "MultipleValues".GetLocalizedResource() : null;